Method of manufacturing magnetic core matrices



$399,874 Patented Aug. 6, 1&6?

3,099,874 METHOD OF MANUFACTURING MAGNETIC CORE MATRICES Sigfrid Schweizerhof, Backnang, Wurttemberg, Germany, assignor to Telefunken G.m.b.H., Berlin, Germany No Drawing. Filed Feb. 2, 1959, Ser. No. 790,383 Claims priority, application Germany Feb. 6, 1958 7 Claims. (Cl. 29--155.5)

The present invention relates to matrices for magnetically storing or switching impulse information and, more particularly, to a new method for manufacturing such matrices.

Matrices of this nature are extensively used in electronic calculators, information processing systems, distributors and similar systems. A standard matrix of this type generally comprises a planar grid arrangement of annular cores interlaced with reading, Writing and inhibition wires. Its operation is well known and will not be described herein in detail, except to point out that the application of an input pulse drives the material of the core, which material has a generally rectangular hysteresis loop, into a saturated condition at one or the other end of its hysteresis loop, the polarity of the staturat-ing current determining the direction of saturation.

These matrices operate satisfactorily, but they are expensive to manufacture, due to the time and care necessary in threading the wires through the minute openings in the cores. In addition, there is a great deal of breakage and waste in the wiring operation of cores which are already partially wired. For this reason, the manufacture of a matrix of, for instance 32 times 32 cores, is uneconomical. Additionally, due to their structure and the type of handling required, there is a practical limit to the amount of additional miniaturization possible on such matrices.

The formation of a matrix from a perforated plate of ferrite having a rectangular hysteresis loop is also known. The matrix is completed by threading the necessary wires through the perforations in the plate. This kind of matrix represents a certain technical advance over that formed of individual annular cores, because it is stronger than the more conventional matrix. Also, the wiring may be applied to the perforated sheet by photo-engraving techniques, but the expense of such a method can be justified only when the matrices are to be mass-produced. The holes in the perforated plate may be made smaller than the openings in the individual cores, thus reducing the amount of energy necessary to produce saturation and ensuring more positive action This latter result is of great advantage when the matrix is fed by transistors. Further, since the holes may be smaller, the spaces between the holes may be smaller, thus reducing the size of the entire matrix over that of one formed of individual cores. However, threading the necessary wires through the perforations, especially the small ones, is still the greatest disadvantage of the matrix formed from a sheet of ferrite. In addition, it is necessary to form a large number of tiny perforations in a ceramic material without chipping and without otherwise damaging the sheet. This requires extreme care and expensive punches and dies.

Another known method of manufacturing a magnetic core matrix is by pressing the necessary wiring into the surfaces of a perforated sheet of ferrite. This method results in a matrix in which the wires are in intimate contact with the ferrite material, still further reducing the amplitude of the pulse necessary to saturate the core material; but it is extremely difficult to produce such a matrix. The ferrite which forms the material of the sheet is a ceramic material and, as most ceramic materials, it must be fired at extremely high temperatures. Pressing the wires into a sheet formed from powdered ferrite does not produce the rectangular hysteresis loop necessary for producing the storage and switching characteristics desired in the matrix. Therefore, the material must be fired and this means, that the wires imbedded in the material being fired must be covered with a heat-resistant material which will not disintegrate during firing and which will not interfere with the operation of the matrix after it is formed. In addition, the heat-resistant covering must be thin to allow for the placement of the necessary wires in the small spaces provided. But even with these precautions, it is virtually impossible to sinter the material to provide the necessary magnetic characteristics without destroying the wires.

It is, therefore, an object of the present invention to provide a new and improved method for the manufacture of a magnetic storage and switching matrix having superior operating characteristics without encountering the difficulties of the prior art methods.

It is another object of this invention to provide a new method of forming a magnetic storage matrix by spraying or sputtering from a gaseous or vapor phase a layer of ferrite upon a network of insulated wires in such a manner that at least the intersecting points of the wires are completely and intimately covered by the magnetic material.

It is a further object of the invention to pnovide a means for coating the wires to assure that the final coating is smooth and continuous and that excessive material does not enter between the intersecting points of the wires, the coating being applied by dipping or spraying, for example. A lacquer which is temperature-resistant, such as a silicone lacquer, may be used was a bath for the wires.

Spraying of molten metals and ceramic substances on bases which cannot be subjected to high temperatures has been known. Suitable spray guns are available for this purpose, these guns using the material to be sprayed in the form of Wires, rods or powder and introducing the material into a flame. In this manner, copper is sprayed on ceramic surfaces and zinc is applied to paper in the manufacture :of capacitors, for example, without harming the base material. It is also possible to spray quartz which, if properly performed, results in a remarkable compact and homogeneous layer, even though the base material is heated to a relatively low temperature, such as the paper in the manufacture :of paper capacitors mentioned above.

When compared with a sheet pressed from powdered ferrite or other magnetic material, the density of ferrite or other material sprayed or sputtered according to the present invention is so high, that no substantial internal demagnetization takes place through the pores. Thus, the desired magnetic properties are obtained and retained. Furthermore, the wires for-mmg the network, or wire fabric, on which the ferrite is deposited, is not harmed in any way, particularly if they are coated with a layer :of temperature-resistant insulating material prior to spraying. A silicone lacquer may be used for this purpose, and it may be applied by dipping or in any other suitable manner.

In addition, it is possible to form the wire cloth in conventional machines in the size and shape finally needed, in a frame if desired, with terminals attached for connection. After coating with an insulator, the fabric can be pressed or otherwise be placed :on the top surface of a sheet of the sin-tered ferrite and a layer of ferrite sprayed or sputtered over the entire matrix, forming a tight bond between the ferrite land the wire mesh. In any case, the sputtering or spraying may be performed in an appropriate atmosphere or in :a vacuum. The wire fabric and the sintered ferrite base may be cooled during the sputtering or spraying by any suitable means, such as refrigerated gas, to prevent the destruction of the wire or of the insulating coating. The wire mesh and, consequently, the entire matrix may be made in the form of a long band and desirable lengths may be cut therefrom, or it may be made in three dimensions rather than in the conventional planar form. Since the ferrite material may be sprayed on objects of any shape, it is possible to make the matrix according to this invention in any geometrical fonm desired, so that matrices may be custom made to fit into limited spaces of odd shapes.

The method of manufacturing magnetic core matrices according to this invention has at least the following advantages:

1) The wire mesh or fabric of the matrix can be readily made on machines which are now used for making wire cloth, and it is possible to make the wire network on a fname with necessary terminals in the sizes needed for a particular purpose, or in larger sheets from which the desired size and shape sheet may he cut. Such method is more economical than the threading of wires through individual cores or perfona-tions.

(2) The signal wires of the matrix which are used for reading, writing, etc, are coated directly with the ferrite material and are not merely placed within an opening in the material, as in the threaded matrices. Therefiore, it is possible to operate the matrices formed by the method of invention with smaller than conventional pulses, allowing the system to be driven by transistors and other small cur-rent devices.

(3) The points of intersection of the wires in the matrix formed according to the invention may be closer together than in more conventionally formed matrices, thus reducing the size of the overall matrix. This decrease in size of the matrices is becoming increasingly important, as they are more generally used in computing land control systems. 7 I

(4) It is possible to repair a magnetic storage matrix made in accordance with the invention, whereas it was necessary to discard conventional matrices with damaged elements. This results in a great saying in time and material.

1. A method of manufacturing a matrix for the mag netic storage or switching of electrical impulse information, said method comprising the steps: of fabricating a network of insulated signalling or switching wires in the form required by the final matrix, and sputtering from a gaseous phase a coating of magnetic material upon said network for surrounding atleast the points of intersection of said wires with said magnetic material, whereby storing or switching elements are obtained at said points of intersection.

2. The method defined in claim 1, wherein the sputtering of the magnetic material on said wire network is accomplished in an atmosphere which enhances the deposition of the magnetic material.

3. The method defined in claim 1, further including the step of cooling said wire network during the sputtering of the magnetic material thereon.

4. A method of manufacturing a magnetic matrix for storing or switching electrical signals, said method comprising the steps of: forming a wire network of insulated signalling or switching wires of the matrix, and spraying the network of wires so formed with a coating of magnetic material for surrounding at least the points of intersection of said wires with said magnetic material, whereby storing or switching elements are obtained at said points of intersection.

5. The method defined in claim 4, further including the step of cooling said wire network during the spraying of the magnetic material thereon.

6. The method of manufacturing a matrix for the magnetic storage or switching of electric impulse information, said method comprising the steps of: fabricating a network of intersecting insulated signalling or switching wires as they are to be provided in the final matrix, coating the network so formed with a heat-resistant insulating layer for surrounding the points of intersection completely and smoothly with a heat-resistant insulating material and sputtering from an essentially vapor phase a magnetic material on said coated network for surrounding the points of intersection of the Wires with magnetic material, whereby storing or switching elements are obtained at said points of intersection.

7. A method of manufacturing a matrix for the magnetic storage or switching of electrical impulse information, said method comprising the steps of: fabricating a network of insulated signalling or switching wires in the form they assume in the final matrix, coating said network with a heat-resistant insulating layer for completely and smoothly surrounding the points of intersection with a heat-resistant insulating material, and spraying said.

network with a magnetic material for surrounding at least the points of intersection of said wires with magnetic material, whereby storing or switching elements are obtained at said points of intersection.

References Cited in the file of this patent UNITED STATES PATENTS 1,555,296 Kirschner Sept. 29, 1925 1,934,643 Rafton Nov. 7, 1933 2,708,788 Cassman et al. May 24, 1955 2,724,103 Ashenhurst Nov. 15, 1955 2,786,779 Long et al. Mar. 26, 1957 2,874,449 De Rooy et al. Feb. 24, 1959 3,040,301 Howatt et 'al June 19, 1962 

1. A METHOD OF MANUFACTURING A MATRIX FOR THE MAGNETIC STORAGE OR SWITCHING OF ELECTRICAL IMPULSE INFORMATION, SAID METHOD COMPRISING THE STEPS: OF FABRICATING A NETWORK OF INSULATED SIGNALLING OR SWITCHING WIRES IN THE FORM REQUIRED BY THE FINAL MATRIX, AND SPUTTERING FROM A GASEOUS PHASE A COATING OF MAGNETIC MATERIAL UPON SAID NETWORK FOR SURROUNDING AT LEAST THE POINTS OF INTERSECTION OF SAID WIRES WITH SAID MAGNETIC MATERIAL, WHEREBY STORING OR SWITCHING ELEMENTS ARE OBTAINED AT SAID POINTS OF INTERSECTION. 